Study On Compressive And Vibration Properties Of Short Basalt Fiber Reinforced Epoxy Resin Solid Beetle Elytron Plate

Under the background of promoting building industrialization,intelligent building and green building,developing new functional structural materials for environmental protection is an inevitable move to respond to the call of the times.Basalt fiber is a kind of environmentally friendly high-performance fiber,and the beetle elytron plate（BEP）has been proved to be a new kind of lightweight sandwich structure with superior mechanical properties than the traditional honeycomb sandwich plate.Meanwhile,foam filling has been proved to effectively improve the structural mechanical properties and thermal insulation performance.Therefore,in order to promote the application of BEP to aerospace and other fields,which need light weight and high strength,thermal insulation and vibration reduction performance,based on the advantages of lightweight bionic structure and green materials,supplemented by foam filling,the compressive and vibration properties of PVC foam filling BEP prepared by short basalt fiber reinforced epoxy resin composites are studied.An integrated molding preparation process is developed to prepare the PVC foam filling short basalt fiber reinforced epoxy resin composites end-trabecular beetle elytron plate(EBEP_fc)and honeycomb plate(HP_fc)with the same honeycomb wall thickness.Firstly,the effect of foam density and height to thickness ratio on the compressive mechanical properties and failure modes of HP_fc and EBEP_fcare investigated via compression experiments.Secondly,the modal parameters and vibration response of HP_fc and EBEP_fc are obtained by modal experiment,and the reasons for the differences in vibration performance between them are discussed.Finally,the parametric study on the natural frequency of HP_fc and EBEP_fcis carried out through ABAQUS,which provides a reference for the rational design of EBEP_fc and its promotion in aerospace and other fields in the future.And it also provides a valuable reference for the research on the bionic application field of BEP.The main conclusions are as follows:（1）Study on compressive mechanical properties of HP_fc and EBEP_fc with different foam densities and height to thickness ratiosHP_fcand EBEP_fc are prepared by the integrated molding preparation process developed by our research group.The compressive mechanical properties and failure modes of HP_fc and EBEP_fc with different foam densities and height to thickness ratios are investigated via quasi-static compression experiments.With increases in foam density and height to thickness ratio,the peak load and energy absorption of EBEP_fcdecrease gradually,while those of HP_fc first increase and then decrease.The specific peak load and specific energy absorption of both decrease significantly.The different lateral constraint of foam make the failure modes of honeycomb walls in outer and inner rings of both HP_fc and EBEP_fc are mainly 45°shear and X-type failure modes,respectively.There is also Y-type failure that between the above two failure modes on the inner ring honeycomb wall of HP_fc with the lowest foam density.Based on the mechanical properties of HP_fc and EBEP_fc,the coupling influence mechanism of the core structure,foam density and height to thickness ratio on the compressive mechanical properties of the two sandwich plates is revealed.It is also found that there is an optimum foam filling density for different sandwich plates.（2）Study on vibration properties of HP_fc and EBEP_fcThe natural frequency,mode shape,damping ratio and acceleration response of HP_fc and EBEP_fc are obtained by modal experiment.The natural frequencies of the first two modes of EBEP_fc are very close to those of HP_fc,and the first two mode shapes of both HP_fc and EBEP_fc are bending and torsion modes,respectively.However,the vibration response of EBEP_fcis significantly lower than that of HP_fc,while the damping ratio is significantly improved.Therefore,EBEP_fchas better vibration reduction performance and can replace HP_fc in engineering field directly.The internal influence mechanism of the enhance effect of foam filling and EBEP_fc with better vibration performance is revealed from the perspective of shear stiffness:foam filling enhances the shear stiffness of the whole core structure and it has more obvious effect on the shear stiffness of HP_fc.Meanwhile,it reduces the shear force proportion of skin and core skeleton,which plays a positive role in protecting skin and core skeleton.Foam filling further enhances the dynamic performance of HP_fcand EBEP_fc.The equivalent cross-section area of EBEP_fc core is higher than that of HP_fc,which makes EBEP_fc core have higher shear stiffness.On the one hand,it makes the skeleton shear force proportion of EBEP_fc higher than that of HP_fc,and on the other hand,it makes the vibration performance of EBEP_fc better.Besides,the EBEP_fc core has lower shear strain energy per unit volume and produces severer friction inside,which results in higher damping ratio of EBEP_fc.（3）Study on the effect of different structural parameters on the natural frequency of EBEP_fcThrough the numerical simulation of EBEP_fc by ABAQUS,the influence degree and basic influence law of some parameters such as face sheet thickness T_f,height to thickness ratioβ,foam densityρ,and aspect ratio a/b on its natural frequency are investigated by the Analysis of Means.The aspect ratio has the most significant influence,while the foam density has the weakest influence.Taking HP_fc as a comparison,the research scope of each parameter is refined,and the influence law and internal influence mechanism of the above parameters on the natural frequencies of the first two modes of HP_fc and EBEP_fc are expounded in detail.The influence of parameter variation on the natural frequencies of HP_fc and EBEP_fc is similar,and the natural frequency of EBEP_fc is always slightly lower than that of HP_fc.Based on the above influence law,some design suggestions for EBEP_fc are proposed.Finally,based on the fact that EBEP_fc has better mechanical properties and lower vibration response while the natural frequency of EBEP_fc is close to that of HP_fc with the same structural parameters,the feasibility and advantages of EBEP_fc in replacing traditional foam filling sandwich structures in vibration reduction and anti-seismic structures are expounded,which provides reference for EBEP_fc in engineering practice.